Oil refineries are under intense pressure to process lower quality crudes for reason of price or availability, or both. Unfortunately, in many cases, oil refiners do not possess enough information and knowledge about certain crudes and crude blends and how they behave in an operating environment to make processing these crudes feasible. Individual refiners only have access to information and knowledge about crudes they have actually tested or used.
In an effort to address the problem of not possessing enough information about certain crudes and how they behave in an operating environment, some refiners have begun to use laboratory simulations to develop predictive models of certain performances. These models, however, are limited and do not address specific, often complex problems that may arise during processing of these crudes and how these problems can be alleviated by using appropriate chemical treatment solutions. U.S. Pat. No. 5,412,581 discloses and claims a process for predicting and evaluating the physical properties of hydrocarbons using spectrometry.
Linear programming systems have also been implemented which focus on defining crude cut and the corresponding cut yield, but these systems do not address the use of treatment chemical in the crude selection mode, nor do they assess the amount of fouling in equipment during processing to allow for a risk assessment of the lower cost crudes. These methods cannot tell refiners how the crude blends will effect operations and equipment. Therefore, refiners lack critical information they require to access the risk and economic viability of using lower quality crudes.
Crude preheat train fouling is not a well-understood phenomena. Many times refiners do not have enough information to determine whether or not the use of a new crude or crude blend is fouling up the refinery equipment, particularly heat exchange networks. Fouling of the heat exchange network can result in rapid decrease in furnace inlet temperature and lead to substantial economic and environmental consequences. Although proper chemical treatment can extend the life of the heat exchangers, lack of quantitative understanding of the phenomenon makes proposing a treatment more challenging. Therefore, it is desirable to have the ability to quantify the fouling propensity of a particular crude being processed and its impact on operating conditions.
Accordingly, there is a need for means for assessing and evaluating crude selection, and predicting the cost and risk associated therewith.
More particularly, there is a need to determine the optimal dosing of the crudes with treatment chemicals so that crude blends including cheaper crudes can be utilized without detrimental effects on the operating equipment of the refineries, such as fouling of the heat exchange networks.
More particularly, what is needed is a methodology and system which enables refineries to process cheaper or opportunity crudes, or blends comprising opportunity crudes, by using models to predict the fouling propensity of said crudes. The methodology should enable refineries to achieve benefits of using cheaper crudes, lower potential treatment chemical costs, increase throughput, extend run lengths and lower operating costs all in a more ecologically beneficial environment.